A Colorado man was sentenced to life in prison without the possibility of parole Monday after pleading guilty to murdering his pregnant wife and their two young daughters and dumping their bodies on an oil work site.

Christopher Watts pleaded guilty on November 6 to three charges of murder in the deaths of his wife, Shanann Watts, and their young daughters. He also pleaded guilty to two counts of murdering a child, one count of unlawful termination of a pregnancy and three counts of tampering with a deceased human body.

Prosecutors have said they agreed not to seek the death penalty in exchange for Watts' guilty plea, after seeking approval from Shanann Watts' family. First-degree murder charges in Colorado require a minimum sentence of life without a chance at parole for adults.

Chris Watts was sentenced Monday. His parents and those of his wife, Shanann, both spoke.

A friend asked police to check on Shanann Watts on Aug. 13 when she could not reach her and grew concerned that the 34-year-old who was pregnant with a third child missed a doctor's appointment. Local police initially handled the search and soon sought support from Colorado investigators and the Federal Bureau of Investigation.

Meanwhile, Christopher Watts spoke to local television reporters from the front porch of the family's home in Frederick; a small town on the plains north of Denver where drilling rigs and oil wells surround booming subdivisions. Watts pleaded for his family to return home, telling reporters their house felt empty without four-year-old Bella and three-year-old Celeste watching cartoons or running to greet him at the door.

Within days, the 33-year-old was arrested and charged with killing his family.

According to court records, Watts admitted to police that he killed his wife. Watts told investigators that he strangled her in "a rage" when he discovered she had strangled their two daughters after he sought a separation.

Prosecutors have since called Watts' account "a flat-out lie."

Authorities have not released autopsy reports or any information about how the mother and daughters died. Prosecutors have said the reports would be released after Christopher Watts' sentencing.

The girls' bodies were found submerged in an oil tank, on property owned by the company Christopher Watts worked for until his arrest. Shanann Watts' body was found buried nearby in a shallow grave.

Police also learned that Christopher Watts was having an affair with a co-worker. Watts had denied that before being arrested.

The killings captured the attention of media across the country and became the focus of true crime blogs and online video channels, aided by dozens of family photos and videos that Shanann Watts shared on social media showing the smiling couple spending time with their children and each other.

Courts records, though, showed the couple's lifestyle caused financial strain at times. They filed for bankruptcy in June 2015, six months after Christopher Watts was hired as an operator for the large oil and gas driller Anadarko Petroleum at an annual salary of about $61,500. At the time, Shanann Watts was working in a children's hospital call center for $18 per hour.

They reported total earnings of $90,000 in 2014 but $70,000 in unsecured claims along with a mortgage of nearly $3,000. The claims included thousands of dollars in credit card debt, some student loans and medical bills.